Disposable viscosity cup



June 3, 1958 M. R. EUVERARD 2,836,975

DIsPosABLE vscosm cup Filed Aug. 2e, 1954 ATTORNEY 5 United States Patent O DISPGSABLE VISCGSITY CUP Maynard R. Euverard, Short Hills, N. J. Application August 26, 1954, Serial No. 452,301

2 Claims. (Cl. 73-55) This invention relates to viscometers and other viscosity-indicating devices, and is concerned with the provision of a cup viscometer of the eiux type so economical to produce as to justify discarding the device after a single use.

The eiiiux type viscosity cup is used by many producers and consumers of chemical coatings for the control of this property. The most popular accepted standard cup available is the Ford type. This type cup is currently available in two ranges, the No. 3 and No. 4, and there is now consideration for the addition of two more ranges, the No. 1 and No. l0. The range of viscosity accommodated by these cups is roughly as follows:

Cup No. Time in Viscosity in Seconds Stokes t0 100 l 0.10 t0 1.00 20 to 100 0.17 to 2.18 20 t0 100 0.55 t0 3.74 20 to 100 l2.00 to 10.00

1 Values not yet definitely established.

The mathematical equation which relates the factors involved is:

taart-g where Vs is viscosity in stokes t is time of efflux in seconds K and C are constants becomes relatively small. Therefore, above a given minimum viscosity in any particular cup it is safe to assume that viscosity is directly proportional to efux time.

The Ford type cup is formed by a vertical cylinder 1.982 inches in diameter and 1.705 inches high, below which cylindrical section is an inverted 60 degree conical section that leads to a removable orifice. These values are the same for all cup numbers, the only difference being in the dimensions of the removable orices. On most cups of this type there is a trough surrounding the upper edge to accommodate overow in lling. In manufacture, the Ford type cup is produced to approximate dimensions given above. The orice is then adjusted to provide desired elux characteristics. This is specified for the No. 4 cup by the following constants:

ICC

'In use this type cup is illed level full after the cup and material to be measured have been adjusted to the desired temperature. Time in seconds is then measured for the material to ow from the cup to the rst break in the eiiiux stream at the cup oriiice. Results may be speciied simply in seconds in No. cup and at degees temperature; or the results may be converted to kinematic viscosity in Stokes by use of the cup equation. To nd the centistoke value the Stoke value is multiplied by 100.

Careful operators can use the Ford type cup described above with errors no greater than 2%. Therefore, for some purposes, especially as a reference standard, it is a very satisfactory and desirable instrument. However, there are three features that could be improved in an instrument of this type where numerous viscosity readings must be made and a very high degree of accuracy is not required. These are:

( l) Reduction of instrument clean-up time.

(2) Reduction of temperature change onmaterial being measured caused by high heat content of large metal cup mass when cup is not properly adjusted to measuring temperature.

(3) Reduction of errors when measuring non-Newtonian materials. This is caused in the standard type cup by clingage to the surfaces of the metal cup which drains oit slowly and does not provide a Well defined break in the orifice stream.

It is an object of the present invention to provide an eiux type viscometer having an accuracy comparable to that of the Ford cup but of such low cost as to justify discarding the device after a single use (i. e., a oneshot viscosity cup). lt is a further inventive object to provide an eilux type viscometer which is devoid of error arising from a poorly defined break in the orifice stream. It is an object of the invention, also, to provide a viscometer, of reasonable accuracy, which does not require adjustment of the temperature of the device to that of the material being tested. I

The above, and other, inventive objects are realized by the device of the present invention, which consists of a pair of disposable paper cups into the bottom of one of which-hereinafter called the orifice cup-there is tted a suitable oiilice member. Since it is desired that results from the one-shot cup be equivalent to the designated Ford type cup the volume held by the two cups should be in the same range. A till line is applied about the inside periphery, near the top of the orifice cup. This is to insure that the same volume is used Whenever measurments are made with this instrument, and also to eliminate diiiculties encountered in filling any vessel just level full. The orice may be of pressed metal, molded plastic, or other material on which internal dimensions can be held constant. As will be seen-later, actual orifice dimensions are dependent on other cup factors, but in order to minimize turbulence and end effects the orifice length should be as large as or larger than the orifice diameter. The orifice may be permanently secured to the bottom of the cup by any suitable means.

A second disposable paper cup-hereinafter called the receiver -cup-is furnished to receive the discharge of the oriiice cup described above. This latter cup also has a ll line, but the same is so located that the volumelof ythe cup below this line is something less than of the volume of the oriiice cup below its till line.

The methods of producing disposable paper cups are such that their volume has very little variation. The orifice selected for these disposable cups must also be held constant with respect to internal diameter and length. Preferably, the till line is so located on the orifice cup in relation to the till line in the receiver intrus cup that the time of efflux from the orilice cup to lill Y Equivalent Ford No. l (K=0.0l) Equivalent Ford No. 3 (l-:0024) Equivalent Fordl No. 4 (K=0.037) Equivalent Ford No. 10 (K=0.l00)

lf this is the case, location of the till line should be adjusted on the orilice cup, only, to permit a common receiver cup to be used for all cup ranges. The cup range may be noted on the orifice cup, and instructions as to use may, if desired, be printedl thereon.

The one-shot cup viscometer can be produced in quantity so that individual variation from the standard Ford type will be no greater than For production control and routine measurements Va spot variation of as much as could probably be tolerated.

Method of use (l) Material to be measured is adjusted to desired temperature.

(2) The operator, While holding a iinger over the orifice, lls the orifice cup to the indicated till line.

(3) A stop watch is started at the same time the operator removes his finger from the orice.

(4) The number of secondsfor the efflux stream to till the receiver cup to the ll line indicated thereon is observed.

(5) This number of seconds is recorded with the number of the cup used.

(6) The measured material is returned to its orginal container or discarded.

' (7) The one-shot viscometer cups are discarded.

Inherent in the one-shot viscometer are the following advantages ynot found in other instruments:

(l) Elimination of instrument clean-up time since the cups are discarded after each measurement.

(2) No time is required to adjust the cups to desired measuring temperature.

(3) Errors due to temperature change are reduced, since the disposable cup is very low in heat content, and even though its temperature is Widely dilerent from that specified for the test there will be no appreciable effect on the material being measured. In addition, temperature change of cup contents due to the surrounding air is reduced, since the one-shot cup is a heat insulator.

(4) Error due to uncertain break in orice stream is eliminated, since the end point is determined when the eiux volume fills the receiver cup to the till line, at which time 10% of the starting volume remains in the orifice cup.

(5) Errors due to orice wear are eliminated. Errors from this source have been found to be quite serious in other cup type instruments especially Where improper cleaning procedures have been practiced.

Illustrative of advantages 2 and 3 above are the following:

In most published works on viscosity measurements it has been stated that even for routine control purposes temperature should be controlled to Within 0.5` C.

Assuming that the temperature of the paper cup has not been adjusted to the selected measuring temperature, the equilibrium effect of the dierence between the temperature of the cup and the selected measuring temperature may be expressed in Vthe basic equation:

t MLSLt-kMcSctl 2- M.S.+MLSL where M2, is gram` weight of cup Sis Yspecific heat of cupv t2 is temperature of equilibrium Ar1 is starting temperature of cup t is starting temperature of liquid ML is gram mass of liquid SL is specific heat liquid The weight of a paper cup according to the invention is approximately 4 grams, and the specific heat of the paper is approximately 0.37. Let it be assumed that the test liquid is petroleum and that the gram mass to be considered is (i. e., approximately 100 ccs.). The specific heat of petroleurn'is 0.511. Let it be assumed further that the temperature of the petroleum has been adjusted to a standard measuring temperature of 25.0 C. but that the temperature of the paper cup is 30.0 C. The resulting temperature, at equilibrium, Willbe:

Y t2=25g15 C. in other words, a difference of 5.0 C. .between the standard measuring temperature and the temperature of the paper cup enfects a change of only 0.15"y C. in the equilibrium temperature, or only about one-third ofthe permissible change. In contrast thereto, a representative brass cup with a gram weight ,of 93 would have effected a change of 0.8 C.; a representative aluminum `cup with a gram Weight of- 5f7 would have effected a change of 1.0n C., and a representative cup formed of mineral iiller phenol-formaldehyde plastic composition with a- Aluminum 1.5040 Brass 0.2600 PlaSiC 0.0008 to 0.0020 Paper 0.0003

This factor of low heat conductivity is importantes it reduces the rate of temperature change of thematerial being measured which may be caused by ambient conditions.

The one-shot viscometer, provides a very convenient,- loW-cost means for making averyj important lphysical measurement. As such it should promote more frequent measurement and closer control of viscosity, which will be beneficial to` both the producer and consumer ofV paints and similar materials. technician time for each viscosity measurement should, in most cases, Ybe several times greater than the cost of the one-shot viscometer. This economic advantage and, in addition, the reduction of the most common sources of error in this type of measurement should makeY the one-shot viscometer a valuable addition to any industry involved with measurement of flow properties `of ymaterials lin the range presently accommodated by the cup type instruments.

The invention will now be described with referen to the accompanying drawings, in which:

Fig. 1 is a perspective view of a viscometer accordingr to the present invention, consisting of an orice cup A and a receiver cup B;

Fig. 2 is an enlarged view showing the components of the orifice member of cup A of Fig. 1; and

Fig. 3 is an enlarged view of the components of an alterative orifice member adapted for use on the orifice cup In Fig. 1 is shown a paper cup 1 of standardized size and dimensions, having the general form of an inverted The savings in cost of laboratory truncated zone, with a rolled upper edge 2 and generally at bottom 3 somewhat inset above a bottom edge 4. The orice member, which is disposed axially of the cup in the bottom 3 of the latter, is constituted by a tubular part 5 extending downwardly through an opening (not shown) in the bottom of cup 1, and associated retaining disc 6, both being formed of molded plastic.

As shown in Fig. 2, the tubular part 5 is provided at its upper edge with an outstanding lange 9 for contacting a substantial portion of the inner bottom surface of cup 1. Retaining disc 6 has a centrally located opening complemental to tubular part 5, and from opening 10 a plurality of spaced radial cuts 11, 11 extend a part of the distance from said opening to the periphery of the disc; retaining disc 6 is adapted to be forced over tubular part 5, after the same has been positioned in the opening provided therefor in the bottom of cup 1, into Contact with the outer surface of bottom 3 to retain the tubular part in fixed position.

A iill line 7 is printed, or otherwise applied, to the inner surface of cup 1 parallel to the top and bottom of the cup and at a slight distance below the top of the same.

Cup B is identical with cup A except that (l) it is not provided with an orifice member, and (2) its iill line 8 is disposed somewhat lower in the cup B than is ill line 7 in cup A, to represent a volume approximately 90% of that represented by fill line 7 of cup A.

The use of this assemblage of orilice and receiver cups has been described hereinbefore and need not be re- 9 peated.

ln lieu of the orilice member illustrated in Figs, l and 2 there may be used an orilice member such as that shown in Fig. 3, consisting of (a) a tubular part having an outstanding flange 16 at its upper edge and threaded portion 17 immediately adjacent the tiange, and (b) retaining disc 13 having an interiorly threaded central opening 19. This tubular part and its associated retaining disc are of pressed metal. In forming cup A according to this embodiment part 15 is located in the central opening in the bottom of the cup and is retained in place by running threaded retaining disc 1S thereonto until the same is tight against the bottom of the cup.

ln further illustration, one specific viscosity cup embodying the present invention was a straight-sided, frustro-conical paper cup approximately 2.70 inches tall and having an internal diameter of 1.80 inches at the bottom and 2.40 inches at the top. The fill line represented a total volume of 125 milliliters. The tubular orifice member had an internal diameter of 0.160 inch and a length of 0.200 inch. The lill line on the companion receiver cup represented a test volume of 110 milliliters. A test volume of iiuid flowed through the oriiice member from the orice cup into the receiver cup in 45 seconds, indicating the viscosity of the fluid to be 1.66 Stokes.

For certain special purposes, it sometimes is desirable that the length of the tubular part of the oriiice member be considerably greater than is the internal diameter of the same. Elongation of the tubular part has the eliect of decreasing the rate of owtor, in other words, of increasing the time of iiow) of the test volume of fluid through the orifice member.

l claim:

l. A disposable or one-use eiiiux-type viscometer consisting of an orifice cup and a receiver cup, said orifice and receiver cups being formed of paper and being identical with each other in shape and size, said orifice cup having a substantially plane bottom, said bottom being provided with a tubular orifice member extending beneath the bottom of the cup and having a length greater than its internal diameter, said orice and re- -ceiver cups having ll lines, parallel to and intermediate the tops and bottoms of the cups, the iill line of the orifice cup representing an arbitrary standard volume of liquid the viscosity of which is to he determined and the ll line of the receiver cup representing a volume somewhat smaller than said standard volume.

2. A disposable or one-use eiiiuX-type viscometer con* sisting of an oriiice cup and a receiver cup, said oriice and receiver cups being formed of paper and being identical with each other in shape and size, said oritice cup being in the form of an inverted truncated cone having a substantially iiat bottom closure at its smaller end and provided in its bottom with a tubular orice member extending beneath the bottom of the cup, said tubular orifice ymember having a length greater than its internal diameter, said orice and receiver cups having till lines, parallel to and intermediate the tops and bottoms of the cups, the fill line of the orifice cup representing an arbitrary standard volume of liquid the viscosity of which is to be determined and the ll line of the receiver cup representing a volume somewhat smaller than said standard volume.

References Cited in the file of this patent UNiTED STATES PATENTS 671,658 Reilly Apr. 9, 1901 1,132,621 Saybolt Mar. 23, 1915 1,553,802 Claypoole Sept. 15, 1925 1,685,896 Woudhuysen et al Oct. 2, 1928 FOREIGN PATENTS 433,286 italy Apr. 5, 1948 951,403 France Apr. 18, 1949 816,914 Germany Oct. l5, 1951 

